1. Field of the Invention
The present invention generally relates to a backlight module and a liquid crystal display apparatus, and more particularly to a backlight module and a liquid crystal display apparatus capable of promoting LED temperature distribution.
2. Description of Prior Art
Nowadays, a liquid crystal display (LCD) is mainly manufactured by producing a backlight module composed by a backlight source, a housing and a diffuser plate first, and then assembling the backlight module with a liquid crystal front panel and a frame to compose a LCD module for manufacturing a final product. Generally, the backlight module which the backlight sources of the liquid crystal display utilizes Cold Cathode Fluorescent Lamps (CCFL) is now substantially replaced by a LED backlight module because the properties of the low power consumption and mercury free of the LED backlight module. Consequently, the CCFL backlight module will be history ultimately. The LED backlight module will replace overall with no doubt.
Now, the LEDs are generally laid out on the light bars in the backlight module utilizing the LEDs as the backlight sources. A predetermined specification will be introduced to select the mass-production LEDs and classify thereof. Generally, the indexes of performance employed for classifying the LEDs includes the brightness, the chrominance, the wavelength or the positive voltage bin of the LEDs. Accordingly, the LEDs can be classified by the aforesaid indexes. The display manufacturer generally selects the LEDs belonging to a major bin to be laid out on the light bars. On the other hand, the backlight uniformity of the display apparatus is extremely severe, therefore, the range to select the LEDs for the display manufacturer is essentially narrowed down. Therefore, the ratio of the selected LEDs in the mass-production LEDs is inevitably too small.
The aforesaid procedure will lead another issue. Because a set of LEDs belonging to the same bin is selected and utilized in the backlight module, and the cooling mechanism of the LEDs around the center is simpler than those at the periphery. Therefore, the temperatures of the LEDs around the center are higher than the temperatures of the LEDs at the periphery. Accordingly, non-uniformity issues of brightness and chrominance of backlight module exist.